17 research outputs found
Design and Biological Evaluation of Antifouling Dihydrostilbene Oxime Hybrids
Source at https://doi.org/10.1007/s10126-018-9802-z. By combining the recently reported repelling natural dihydrostilbene scaffold with an oxime moiety found in many marine
antifoulants, a library of nine antifouling hybrid compounds was developed and biologically evaluated. The prepared compounds
were shown to display a low antifouling effect against marine bacteria but a high potency against the attachment and growth of
microalgae down to MIC values of 0.01 ÎŒg/mL for the most potent hybrid. The mode of action can be characterized as repelling
via a reversible non-toxic biostatic mechanism. Barnacle cyprid larval settlement was also inhibited at low ÎŒg/mL concentrations
with low levels or no toxicity observed. Several of the prepared compounds performed better than many reported antifouling
marine natural products. While several of the prepared compounds are highly active as antifoulants, no apparent synergy is
observed by incorporating the oxime functionality into the dihydrostilbene scaffold. This observation is discussed in light of
recently reported literature data on related marine natural antifoulants and antifouling hybrids as a potentially general strategy for
generation of improved antifoulants
Lipid accumulation controls the balance between surface connection and scission of caveolae
Caveolae are bulb-shaped invaginations of the plasma membrane (PM) that undergo scission and fusion at the cell surface and are enriched in specific lipids. However, the influence of lipid composition on caveolae surface stability is not well described or understood. Accordingly, we inserted specific lipids into the cell PM via membrane fusion and studied their acute effects on caveolae dynamics. We demonstrate that sphingomyelin stabilizes caveolae to the cell surface, whereas cholesterol and glycosphingolipids drive caveolae scission from the PM. Although all three lipids accumulated specifically in caveolae, cholesterol and sphingomyelin were actively sequestered, whereas glycosphingolipids diffused freely. The ATPase EHD2 restricts lipid diffusion and counteracts lipid-induced scission. We propose that specific lipid accumulation in caveolae generates an intrinsically unstable domain prone to scission if not restrained by EHD2 at the caveolae neck. This work provides a mechanistic link between caveolae and their ability to sense the PM lipid composition
Preparation of Simple Bicyclic Carboxylate-Rich Alicyclic Molecules for the Investigation of Dissolved Organic Matter
Dissolved organic matter (DOM) is a vast and complex chemical mixture that plays a key role in the mediation of the global carbon cycle. Fundamental understanding of the source and fate of oceanic organic matter is obscured due to poor definition of the key molecular contributors to DOM, which limits accurate sample analysis and prediction of the Earth's carbon cycle. Previous work has attempted to define the components of the DOM through a variety of chromatographic and spectral techniques. However, modern preparative and analytical methods have not isolated or unambiguously identified molecules from DOM. Therefore, previously proposed structures are based solely on the mixture's aggregate properties and do not accurately describe any true individual molecular component. In addition to this, there is a lack of appropriate analogues of the individual chemical classes within DOM, limiting the scope of experiments that probe the physical, chemical, and biological contributions from each class. To address these problems, we synthesized a series of analogues of carboxylate-rich alicyclic molecules (CRAM), a molecular class hypothesized to exist as a major contributor to DOM. Key analytical features of the synthetic CRAMs were consistent with marine DOM, supporting their suitability as chemical substitutes for CRAM. This new approach provides access to a molecular toolkit that will enable previously inaccessible experiments to test many unproven hypotheses surrounding the ever-enigmatic DOM
Characterization of a Newly Available Coastal Marine Dissolved Organic Matter Reference Material (TRM-0522)
Recent methodological advances have greatly increased our ability to characterize aquatic dissolved organic matter (DOM) using high-resolution instrumentation, including nuclear magnetic resonance (NMR) and mass spectrometry (HRMS). Reliable DOM reference materials are required for further method development and data set alignment but do not currently exist for the marine environment. This presents a major limitation for marine biogeochemistry and related fields, including natural product discovery. To fill this resource gap, we have prepared a coastal marine DOM reference material (TRM-0522) from 45 m deep seawater obtained âŒ1 km offshore of Swedenâs west coast. Over 3000 molecular formulas were assigned by direct infusion HRMS, confirming sample diversity, and the distribution of formulas in van Krevelen space was typical for a marine sample, with the majority of formulas in the region H/C 1â1.5 and O/C 0.3â0.7. The extracted DOM pool was more nitrogen (N)- and sulfur (S)-rich than a typical terrestrial reference material (SRFA). MZmine3 processing of ultrahigh-performance liquid chromatography (UPLC)-HRMS/MS data revealed 494 resolvable features (233 in negative mode; 261 in positive mode) over a wide range of retention times and masses. NMR data indicated low contributions from aromatic protons and, generally speaking, low lignin, humic, and fulvic substances associated with terrestrial samples. Instead, carboxylic-rich aliphatic molecules were the most abundant components, followed by carbohydrates and aliphatic functionalities. This is consistent with a very low specific UV absorbance SUVA254 value of 1.52 L mg Câ1 mâ1. When combined with comparisons with existing terrestrial reference materials (Suwannee River fulvic acid and Pony Lake fulvic acid), these results suggest that TRM-0522 is a useful and otherwise unavailable reference material for use in marine DOM biogeochemistry
Preparation of Simple Bicyclic Carboxylate-Rich Alicyclic Molecules for the Investigation of Dissolved Organic Matter
Dissolved organic
matter (DOM) is a vast and complex chemical mixture
that plays a key role in the mediation of the global carbon cycle.
Fundamental understanding of the source and fate of oceanic organic
matter is obscured due to poor definition of the key molecular contributors
to DOM, which limits accurate sample analysis and prediction of the
Earthâs carbon cycle. Previous work has attempted to define
the components of the DOM through a variety of chromatographic and
spectral techniques. However, modern preparative and analytical methods
have not isolated or unambiguously identified molecules from DOM.
Therefore, previously proposed structures are based solely on the
mixtureâs aggregate properties and do not accurately describe
any true individual molecular component. In addition to this, there
is a lack of appropriate analogues of the individual chemical classes
within DOM, limiting the scope of experiments that probe the physical,
chemical, and biological contributions from each class. To address
these problems, we synthesized a series of analogues of carboxylate-rich
alicyclic molecules (CRAM), a molecular class hypothesized to exist
as a major contributor to DOM. Key analytical features of the synthetic
CRAMs were consistent with marine DOM, supporting their suitability
as chemical substitutes for CRAM. This new approach provides access
to a molecular toolkit that will enable previously inaccessible experiments
to test many unproven hypotheses surrounding the ever-enigmatic DOM
Sulfadiazine Masquerading as a Natural Product from Scilla madeirensis (Scilloideae)
The structure of 2,4-(4'-aminobenzenamine)pyrimidine (1), a pyrimidine alkaloid previously isolated from the bulbs of Scilla madeirensis (Asparagaceae, synonym Autonoe madeirensis), has been revised. These conclusions were met via comparison of reported NMR and EIMS data with those obtained from synthetic standards. The corrected structure is the antibiotic sulfadiazine (2), which has likely been isolated as a contaminant from the site of collection. The reported bioactivity of 1 as an alpha(1)-adrenoceptor antagonist should instead be ascribed to sulfadiazine. Our findings appear to show another example of an anthropogenic contaminant being identified as a natural product and emphasize the importance of considering the biosynthetic origins of isolated compounds within a phylogenetic context
Palladium-Mediated Approach to Coumarin-Functionalized Amino Acids
Incorporation of the fluorogenic l-(7-hydroxycoumarin-4-yl)Âethylglycine
into proteins is a valuable biological tool. Coumarins are typically
accessed via the Pechmann reaction, which requires acidic conditions
and lacks substrate flexibility. A Pd-mediated coupling is described
between <i>o</i>-methoxyboronic acids and a glutamic acid
derived (<i>Z</i>)-vinyl triflate, forming latent coumarins.
Global deprotection with BBr<sub>3</sub> forms the coumarin scaffold
in a single step. This mild and scalable route yielded five analogues,
including a probe suitable for use at lower pH
A Genetically Encoded Picolyl Azide for Improved Live Cell Copper Click Labeling
Bioorthogonal chemistry allows rapid and highly selective reactivity in biological environments. The copper-catalyzed azide-alkyne cycloaddition (CuAAC) is a classic bioorthogonal reaction routinely used to modify azides or alkynes that have been introduced into biomolecules. Amber suppression is an efficient method for incorporating such chemical handles into proteins on the ribosome, in which noncanonical amino acids (ncAAs) are site specifically introduced into the polypeptide in response to an amber (UAG) stop codon. A variety of ncAA structures containing azides or alkynes have been proven useful for performing CuAAC chemistry on proteins. To improve CuAAC efficiency, biologically incorporated alkyne groups can be reacted with azide substrates that contain copper-chelating groups. However, the direct incorporation of copper-chelating azides into proteins has not been explored. To remedy this, we prepared the ncAA paz-lysine (PazK), which contains a picolyl azide motif. We show that PazK is efficiently incorporated into proteins by amber suppression in mammalian cells. Furthermore, PazK-labeled proteins show improved reactivity with alkyne reagents in CuAAC
Characterization of a Newly Available Coastal Marine Dissolved Organic Matter Reference Material (TRM-0522)
Recent methodological advances have greatly increased
our ability
to characterize aquatic dissolved organic matter (DOM) using high-resolution
instrumentation, including nuclear magnetic resonance (NMR) and mass
spectrometry (HRMS). Reliable DOM reference materials are required
for further method development and data set alignment but do not currently
exist for the marine environment. This presents a major limitation
for marine biogeochemistry and related fields, including natural product
discovery. To fill this resource gap, we have prepared a coastal marine
DOM reference material (TRM-0522) from 45 m deep seawater obtained
âŒ1 km offshore of Swedenâs west coast. Over 3000 molecular
formulas were assigned by direct infusion HRMS, confirming sample
diversity, and the distribution of formulas in van Krevelen space
was typical for a marine sample, with the majority of formulas in
the region H/C 1â1.5 and O/C 0.3â0.7. The extracted
DOM pool was more nitrogen (N)- and sulfur (S)-rich than a typical
terrestrial reference material (SRFA). MZmine3 processing of ultrahigh-performance
liquid chromatography (UPLC)-HRMS/MS data revealed 494 resolvable
features (233 in negative mode; 261 in positive mode) over a wide
range of retention times and masses. NMR data indicated low contributions
from aromatic protons and, generally speaking, low lignin, humic,
and fulvic substances associated with terrestrial samples. Instead,
carboxylic-rich aliphatic molecules were the most abundant components,
followed by carbohydrates and aliphatic functionalities. This is consistent
with a very low specific UV absorbance SUVA254 value of
1.52 L mg Câ1 mâ1. When combined
with comparisons with existing terrestrial reference materials (Suwannee
River fulvic acid and Pony Lake fulvic acid), these results suggest
that TRM-0522 is a useful and otherwise unavailable reference material
for use in marine DOM biogeochemistry
Characterization of a Newly Available Coastal Marine Dissolved Organic Matter Reference Material (TRM-0522)
Recent methodological advances have greatly increased
our ability
to characterize aquatic dissolved organic matter (DOM) using high-resolution
instrumentation, including nuclear magnetic resonance (NMR) and mass
spectrometry (HRMS). Reliable DOM reference materials are required
for further method development and data set alignment but do not currently
exist for the marine environment. This presents a major limitation
for marine biogeochemistry and related fields, including natural product
discovery. To fill this resource gap, we have prepared a coastal marine
DOM reference material (TRM-0522) from 45 m deep seawater obtained
âŒ1 km offshore of Swedenâs west coast. Over 3000 molecular
formulas were assigned by direct infusion HRMS, confirming sample
diversity, and the distribution of formulas in van Krevelen space
was typical for a marine sample, with the majority of formulas in
the region H/C 1â1.5 and O/C 0.3â0.7. The extracted
DOM pool was more nitrogen (N)- and sulfur (S)-rich than a typical
terrestrial reference material (SRFA). MZmine3 processing of ultrahigh-performance
liquid chromatography (UPLC)-HRMS/MS data revealed 494 resolvable
features (233 in negative mode; 261 in positive mode) over a wide
range of retention times and masses. NMR data indicated low contributions
from aromatic protons and, generally speaking, low lignin, humic,
and fulvic substances associated with terrestrial samples. Instead,
carboxylic-rich aliphatic molecules were the most abundant components,
followed by carbohydrates and aliphatic functionalities. This is consistent
with a very low specific UV absorbance SUVA254 value of
1.52 L mg Câ1 mâ1. When combined
with comparisons with existing terrestrial reference materials (Suwannee
River fulvic acid and Pony Lake fulvic acid), these results suggest
that TRM-0522 is a useful and otherwise unavailable reference material
for use in marine DOM biogeochemistry